Cook over medium heat until the water just starts to boil. Add in 1 cup of granulated sugar at this point and stir continuously until the sugar is fully dissolved. This should only take about 15 seconds! The mixture should look clear.
Remove from heat and stir in 1 tsp of peppermint extract. Waiting to add the extract until you've removed that pan from heat will prevent it from evaporating and losing some of its flavor. I find 1 tsp of peppermint extract is the perfect amount for my palette, but if you like a less strong peppermint flavor I recommend adding 1/2 tsp.
Pour into a separate container and cool to room temperature. I like to keep my simple syrup in glass containers or mason jars for easy storage.
If you're making this in advance, it can be stored in an airtight container in the fridge for up to a month.
Video
Notes
How Much Peppermint Simple Syrup Does this Recipe Make?
This recipe makes about 10 oz. or 1 1/4 cups of peppermint simple syrup. This recipe can be halved, quartered, or doubled if need.
Like I mentioned above, this recipe is pretty straight forward! However, there are some substitutions and swaps you can make if needed.
Water - Room temperature tap water works great in this recipe. I live in Seattle so our tap water tastes great, but if you live somewhere where the tap water isn't quite as tasty you may want to use filtered or bottled water.
Granulated Sugar - I like using granulated sugar because it's what I usually have on hand, but you can also use extra fine sugar or caster sugar.
Peppermint Exact - Any peppermint extract will work, but I recommend using good quality extract because it has a huge impact of the flavor of this syrup. Make sure you don't use peppermint oil or peppermint "flavor."
How to Store this Peppermint Simple Syrup
This recipe can be made in advance or leftovers can be stored in an airtight container in the fridge for up to a month. I usually keep mine in a mason jar but any container with a good lid should work just fine.